Laser processing method, laser welding method, and laser processing apparatus

Abstract

A processing method including steps for splitting a single beam into a plurality of beams including a zero-order diffracted beam, by diffracting the single beam by a diffractive element, for turning an array of focused beam spots obtained from the plurality of beams about the center of the zero-order diffracted beam according to the direction of an array of welding points where parts mounted on a circuit board are welded to the board, for causing a spot interval between focused beam spots in the array to agree with the interval between the plurality of welding points by adjusting the distance from the diffractive element to the board, and for increasing the intensity of the plurality of beams, to a welding intensity, and connecting the parts by simultaneously irradiating the welding points with the focused beam spots in the array having the determined direction and spot interval.

1. A laser processing method, comprising:
 a beam-splitting step for splitting a single laser beam into a plurality of laser beams including a zero-order diffracted laser beam, by diffracting the single laser beam by a diffractive optical element; 
 a direction setting step of turning an array of focused beam spots obtained from the plurality of laser beams about the zero-order diffracted laser beam to align the array of focused beam spots in accordance with a direction of an array of a plurality of processing points of a work; 
 an interval setting step for causing an interval between the focused beam spots in the array to be in agreement with an interval between the plurality of processing points in the array, by adjusting the distance from the diffractive optical element to the work; and 
 a processing step for increasing the intensity of the plurality of laser beams to such an intensity that is necessary to process the work, and processing the work by simultaneously irradiating the plurality of processing points with the focused beam spots in the array having the direction and the interval determined in the preceeding steps; 
 wherein the respective setting steps are executed after the zero-order diffracted laser beam, which has passed through the diffractive optical element, is caused to be in agreement with one of the processing points. 
 
   
   
     2. A laser welding method, comprising:
 a beam-splitting step for splitting a single laser beam into a plurality of laser beams including a zero-order diffracted laser beam by diffracting the single laser beam by a diffractive optical element; 
 a direction setting step of turning an array of focused beam spots obtained from the plurality of laser beams about the zero-order diffracted laser beam in accordance with a direction of an array of a plurality of welding points at which parts mounted on a printed circuit board are welded to the board; 
 an interval setting step for causing an interval between the focused beam spots in the array to be in agreement with an interval between the plurality of welding points in the array by adjusting the distance from the diffractive optical element to the board; and 
 a connecting step for increasing the intensity of the plurality of laser beams to such an intensity that is necessary for welding, and connecting the parts to the board by simultaneously irradiating the plurality of welding points with the focused beam spots in the array having the direction and the interval determined in the preceeding steps. 
 
   
   
     3. A laser welding method according to  claim 2 , wherein the respective setting steps are executed after the zero-order diffracted laser beam, which has passed through the diffractive optical element, is caused to be in agreement with one of the welding points. 
   
   
     4. A laser welding method according to  claim 2 , wherein the connection is made by welding using a filler material. 
   
   
     5. A laser apparatus comprising:
 a laser oscillator; 
 a diffractive optical element for splitting a single laser beam emitted from the laser oscillator into a plurality of laser beams that include a zero-order diffracted laser beam and are used in processing; 
 a turning unit for setting the diffractive optical element at a a desired angle by turning it about the optical axis thereof; and 
 a moving unit for positioning the diffractive optical element on the optical axis by sliding it over a desired distance along the optical axis; 
 wherein:
 the diffractive optical element is one-dimensional relief grating; 
 the zero-order diffracted laser beam is in alignment with the optical azis and in agreement with a processing point; and 
 the moving unit positions the diffractive optical element such that the plurality of laser beams are in agreement with an interval between a plurality of processing points. 
 
 
   
   
     6. A laser processing apparatus according to  claim 5 , comprising a focusing unit for focusing a laser beam incident on the diffractive optical element. 
   
   
     7. A laser processing apparatus according to  claim 5 , comprising an optical axis positioning unit for moving the laser beam incident on the diffractive optical element together with the diffractive optical element in a direction orthogonal to across the optical axis. 
   
   
     8. A laser processing apparatus according to  claim 5 , comprising a solder dispenser for supplying solder to the laser irradiation points on a work.